FIG. 1A illustrates a schematic view of a conventional horizontal light emitting diode. Referring to FIG. 1A, the horizontal light emitting diode 1 includes an epitaxial substrate 11, an epitaxial structure 12 grown from the epitaxial substrate 11 by an epitaxy growth process, and an electrode unit 13 disposed on the epitaxial structure 12 for providing electrical energy. The epitaxial substrate 11 is made of a material such as sapphire or SiC so that an epitaxial growth of a gallium-nitride-based (GaN-based) semiconductor material can be achieved on the epitaxial substrate 11.
The epitaxial structure 12 is usually made of the GaN-based semiconductor material. During the epitaxy growth process, the GaN-based semiconductor material epitaxially grows up from the epitaxial substrate 11 to form an n-type doped layer 121 and a p-type doped layer 122. When the electrical energy is applied to the epitaxial structure 12, a light emitting portion 123 at a junction of the n-type doped layer 121 and the p-type doped layer 122 will generate an electron-hole capture phenomenon. As a result, the electrons of the light emitting portion 123 will fall to a lower energy level and release energy with a photon mode. In one embodiment, the light emitting portion 123 is a multiple quantum well (MQW) structure capable of restricting a spatial movement of the electrons and the holes. Thus, a collision probability of the electrons and the holes is increased so that the electron-hole capture phenomenon occurs easily, thereby enhancing lighting emitting efficiency.
The electrode unit 13 includes a first electrode 131 and a second electrode 132. The first electrode 131 and the second electrode 132 are respectively in an ohmic contact with the n-type doped layer 121 and the p-type doped layer 122 and configured to provide electrical energy to the epitaxial structure 12. When a voltage is applied between the first electrode 131 and the second electrode 132, an electric current flow from the second electrode 132 to the first electrode 131 thru the epitaxial substrate 11 and is horizontally distributed in the epitaxial structure 12. Thus, a number of photons are generated by a photoelectric effect in the epitaxial structure 12. The horizontal light emitting diode 1 emits light from the epitaxial structure 12 due to the horizontally distributed electric current.
A manufacturing process of the horizontal light emitting diode is simple. However, the substrate of the horizontal light emitting diode is mostly a non-conductive sapphire substrate, with a positive electrode and a negative electrode of the horizontal light emitting diode 1 located on the same side (i.e., a co-planar electrodes configuration). In the horizontal light emitting diode 1 with the co-planar electrodes configuration, the electric current is non-uniform, which can cause a current crowding problem, a non-uniformity light emitting problem and a thermal accumulation problem, etc. As a result, the light emitting efficiency of the horizontal light emitting diode can be decreased, and even the horizontal light emitting diode can become damaged.
Generally, the current crowding problem can be reduced by improving the configuration of the electrodes or by changing the geometric shapes of the electrodes. For example, by extending the lengths of a P electrode and an N electrode, the current path from the P electrode to the N electrode is increased to avoid over crowding in the current path.
Referring to FIG. 1B, a conventional finger-shaped electrodes configuration is shown. The finger-shaped electrodes configuration improves the uniformity of the electric current by extending the lengths of the electrodes over the surface of the configuration. It should be appreciated that the more interdigitated structures the finger-shaped electrodes configuration has, the more uniformly the electric current distributes. However, too much interdigitated structures will cause a reduction of a light output area because of a shading effect. To overcome such shading effect, vertical light emitting diodes have been developed.
FIG. 2 illustrates a schematic view of a conventional vertical light emitting diode 2. The conventional vertical light emitting diode 2 includes an epitaxial structure 22 and an electrode unit 23 disposed on the epitaxial structure 22 for providing electrical energy. Similar to the diode of FIG. 1, the epitaxial structure 22 can be made of a GaN-based semiconductor material by an epitaxy growth process. During the epitaxy growth process, the GaN-based semiconductor material epitaxially grows up from an epitaxial substrate (not shown) to form an n-type doped layer 221, an MQW structure 223 and a p-type doped layer 222. Then, the electrode unit 23 is bonded to the epitaxial structure 22 after stripping the epitaxial substrate. The electrode unit 23 includes a first electrode 231 and a second electrode 232. The first electrode 231 and the second electrode 232 are respectively in ohmic contact with the n-type doped layer 221 and the p-type doped layer 222. In addition, the second electrode 232 can adhere to a heat dissipating substrate 24 so as to increase the heat dissipation efficiency. When a voltage is applied between the first electrode 231 and the second electrode 232, an electric current vertically flows. Thus, the conventional vertical light emitting diode 2 can effectively improve the current crowding problem, the non-uniformity light emitting problem and the thermal accumulation problem of the conventional horizontal light emitting diode 1. However, the shading effect of the electrodes still exists in the conventional vertical light emitting diode 2, which causes a reduction of the light emitting area. Furthermore, a manufacturing process of the conventional vertical light emitting diode 2 is complicated. For example, the epitaxial structure 22 is prone to be damaged by high heat when adhering the second electrode 232 to the heat dissipating substrate 24.
In view of the problems discussed above with reference to FIG. 1 and FIG. 2, what is needed is a semiconductor light emitting component applied to a light emitting diode so as to overcome the above disadvantages of the conventional horizontal light emitting diode and the conventional vertical light emitting diode.